It's really hard to give more than a guesstimate, c4f, because everyone's oven is different. It's been a long while since I've done this recipe with a leg that large, so I don't remember. But in any case, everything goes so speedily in my convection oven that if I roasted by time, overcooking would become "normal!" I highly recommend a digital probe thermometer.

The last time I did a 5-pound with this recipe, it was done in under 40 minutes.